A refrigeration cycle is a cycle of a series of thermodynamic processes of absorbing heat from a low-temperature heat source and giving heat to a high-temperature heat source. A refrigeration cycle generally includes a compressor, a condenser, an expansion valve, and an evaporator.
A compressor compresses refrigerant, and discharges refrigerant gas of high temperature and high pressure. A condenser condenses the refrigerant of high temperature and high pressure discharged from the compressor into liquid refrigerant of intermediate temperature and high pressure or low temperature and high pressure. An expansion valve expands the refrigerant of intermediate temperature and high pressure or low temperature and high pressure into a refrigerant of low temperature and low pressure. The expanded refrigerant is evaporated in an evaporator. At this time, a temperature and a pressure of the refrigerant drop more. Since the refrigerant absorbs ambient heat when it is evaporated, the ambient air is cooled down.
The refrigerant circulating through the cycle as described above is sucked again into the compressor to be compressed. Then, the refrigerant circulates repeatedly through the aforementioned cycle. The evaporator absorbs ambient heat, and thereby generates cold air. A refrigerator is constituted such that cold air is blown into a refrigerating compartment by a fan to cool down the interior of the refrigerating compartment.
A conventional refrigerator includes a freezing compartment, a refrigerating compartment and the above-described refrigeration cycle device in such a way that the evaporator is mounted in the freezing compartment to generate cold air having a temperature zone necessary for the freezing compartment, and a portion of the cold air in the freezing compartment is supplied into the refrigerating compartment to cool down the interior of the refrigerating compartment. However, the conventional refrigerator has a problem such that the temperature distribution in the refrigerating compartment is very irregular and also the temperature distribution in the freezing compartment becomes irregular because the cold air is supplied from the freezing compartment into the refrigerating compartment.
Accordingly, in order to solve such a problem, there has been required a technique capable of controlling independently the temperature in the freezing compartment and the refrigerating compartment and maintaining the temperature distribution in the freezing compartment and the refrigerating compartment as regular.
Further, the conventional refrigerator includes only the freezing compartment which is a cooling compartment having a relatively low-temperature zone and the refrigerating compartment which is a cooling compartment having a relatively high-temperature zone. Therefore, there has been required a technique capable of satisfying a user's desire by providing a refrigerator with plural cooling compartments having various temperature zones, for example, a cooling compartment having an intermediate temperature zone between the temperature zones in the refrigerating compartment and the freezing compartment, a cooling compartment having a temperature zone higher than the temperature zone in the refrigerating compartment, and the like.